For the past 20 years Erikson, a sociology professor at Yale University, has studied comunities stunned by recent disasters. His first subject, Buffalo Creek, W. Va., which suffered from the break of an earthen dam in 1972, led him to write Everything in Its Path. Among the seven communities examined here are an Indian reserve in Canada whose water supply was contaminated by mercury, a Colorado neighborhood threatened by gasoline seeping from storage tanks, the towns near the Three Mile Island nuclear plant that faced the possibility of radiation contamination. Erikson found a consistent pattern: loss of self-esteem and faith in institutions, and heightened senses of dread and vulnerability. He finds similar responses among the homeless. Describing this kind of trouble as the product of human error, he reviews the decision to deploy the atomic bomb in WW II and addresses the plan to store nuclear waste at Yucca Mountain in Nevada. In the epilogue to these gripping case studies, Erikson advances the illuminating suggestion that communities can experience trauma just as individauls can. Photos. (Mar.)